This application claims the priority of Japanese Patent Application No. 2000-68384 filed on Mar. 13, 2000 which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to an electronic endoscope apparatus, and more specifically to a configuration and control of a device enabling observation of an object by optically and electronically enlarging the object.
2. Description of the Prior Art
Recently, an electronic endoscope apparatus, etc. has been provided with a movable lens for variable power in an objective system of a scope tip, the movable lens is driven in an optical axis direction by an actuator, etc. so that an image of the object can be optically enlarged. The optically enlarged image is captured by a solid-state image pickup device such as a CCD (charge coupled device), etc., and an enlarged image of the object is displayed on the monitor by performing various image processes by a processor device on a video signal (image signal) output from the CCD.
3. Object of the Invention
On the other hand, in the electronic endoscope, an image obtained by the above mentioned CCD has been electronically enlarged in an image process. Recently, it has been suggested that an image can be enlarged and displayed by combining optically variable power with electrically variable power by the above mentioned electronic objective system. The variable power operation based on the two types of variable power can be performed using the same variable power switch, etc.
However, when the optically variable power and the electronically variable power are realized by the same operating switch, there is a merit that a variable power operation can be continuously performed, but there is also a demerit that an operator cannot easily determine when the optically variable power is to be switched to the electronically variable power, and vice versa, or cannot easily determine whether the current image is enlarged by the optically variable power operation or the electronically variable power operation. That is, as compared with the optically variable power which does not lower the quality of an image when it is variably powered, the electronically variable power deteriorates the quality of an image, for example, when the image is enlarged. Therefore, when correct determination is required, it is necessary to be informed which variable power operation is adopted for the screen display.
The present invention has been developed to solve the above mentioned problems, and aims at providing an electronic endoscope provided with a variable power function capable of easily determining when the optically variable power is switched to the electronically variable power and vice versa.
To attain the above mentioned purpose, the present invention includes an optically variable power mechanism having a movable lens for variable power built in an optical objective system provided at the tip of the endoscope for optically obtaining an enlarge image, an electronically variable power circuit for electronically enlarging an image captured through the above mentioned optical objective system, a variable power switch for operating the variable power of the optically variable power mechanism and the electronically variable power circuit, and a control circuit for controlling the variable power operation performed by the variable power switch to temporarily stop the operation when the optically variable power and the electronically variable power are switched from each other during the operation of the variable power switch.
The above mentioned control circuit can be designed such that the variable power operation can be temporarily stopped by setting a time lag for a predetermined time when the optically variable power and the electronically variable power are switched from each other.
When the variable power operation is temporarily stopped based on the above mentioned time lag, means for informing an operator that the optically variable power is switched into the electronically variable power or vice versa is provided.
With the above mentioned configuration, for example, the optically variable power can be invoked in a state in which an image is not enlarged, and the electronically variable power can be invoked at the enlargement (near) end of the optically variable power. As a result, when the same switch is used to change the optically variable power into the electronically variable power, or to change the electronically variable power into the optically variable power, for example, the switching operation is nullified. That is, the variable power operation cannot work unless the variable power switch is operated again. Therefore, the operator can successfully determine or discriminate the time when the optically variable power and the electronically variable power are switched (changed) from each other. When they are switched, the variable power operation can be stopped for a predetermined time by entering any variable power operation with a time lag set for a predetermined time. In this case, it is desired to indicate on the monitor that the optically variable power is switched into the electronically variable power or vice versa.